Analysing Hitler’s DNA for a TV gimmick tells us nothing useful

If you resort to mentioning Adolf Hitler, some say, you have lost the argument. If you resort to sequencing Hitler’s DNA to try to get more eyeballs for your TV channel, I would say you have just plain lost it.

And yet the UK’s Channel 4 has done just that with Hitler’s DNA: Blueprint of a dictator, which will be broadcast this Saturday. I have forced myself to watch it, so you don’t have to.

The DNA came from a blood-soaked piece of fabric cut from the sofa on which Hitler shot himself in 1945, which now resides in a US museum. The genome obtained has gaps due to the age of the sample, but the Y chromosome is said to match that of a male relative of Hitler, suggesting it is genuine.

If this had been done purely as an academic effort, to add a little to our knowledge by, for instance, revealing whether Hitler had a Jewish grandfather as rumoured (he didn’t, according to the DNA), it would arguably be OK. Instead, we have a sensationalist two-part documentary claiming this DNA evidence “will change the way we think about Hitler”.

The trouble with this is that it implies genetic determinism – that Hitler was somehow destined to do the terrible things he did because of his genes. To be clear, the documentary doesn’t make this specific claim, but it comes pretty close – what else could “Blueprint of a dictator” mean?

This is equivalent to arguing that if we made lots of Hitler clones, they would all end up killing millions, too. This isn’t an experiment we can – or would ever want to – do, but there are plenty of clones in the world, in the form of identical twins, who share the same DNA. Twin studies have been used to estimate the extent to which all kinds of traits and conditions are due to genes rather than the environment.

Now, there are many issues with twin studies, not least that twins usually grow up in the same environment, so it is impossible to completely disentangle genetic and environmental influences. Even so, the highest twin-based estimates for the heritability of criminality – probably the closest we can get to being a genocidal dictator – are less than 50 per cent. So there is no reason to think most Hitler clones would be monsters.

Then there is the fact that our understanding of the human genome is very much in its infancy. We still can’t predict simple traits such as eye colour with 100 per cent accuracy, let alone much more complex traits involving the interaction of the brain with the environment.

What we can do is look for genetic variants that have been statistically linked to a higher risk of conditions such as autism. People can then be given a “polygenic score” for each condition. The thing is, getting a very high polygenic score for autism doesn’t necessarily mean an individual definitely is autistic. There are many reasons for this: environmental factors matter too, the association between trait and variant might be spurious, we haven’t identified all the variants that matter, and so on.

“Due to inconsistent associations and limited generalizability, it must be emphasized that the autism polygenic score in its current state does not have clinical utility,” a meta-analysis concluded earlier this year.

According to the documentary, Hitler’s genome scores very highly for autism, along with the mental health conditions schizophrenia, bipolar disorder and antisocial behaviour or psychopathy. It also has an above-average score for ADHD. But there is already a long history of claiming Hitler had these kinds of mental conditions on the basis of his behaviour. The genetic evidence doesn’t prove anything and the diagnostic criteria for these conditions don’t include genetic data.

But more to the point, so what if he did have any of these conditions? Do any of these labels explain anything? As Simon Baron-Cohen at the University of Cambridge says in the documentary, the neglect and abuse Hitler experienced at the hands of his alcoholic father is “much more relevant to understanding why he grew up with hate and anger”.

Later, we are told that schizophrenia-related traits can be linked to creativity and unconventional thinking, which might explain his political and military successes. Really? This is pure speculation.

To me, that is the issue with analysing Hitler’s genome. You can make all these plausible-sounding connections with what we know about his personality and actions, but they could all be completely spurious. What’s more, it risks worsening the stigma already associated with conditions like autism, schizophrenia and bipolar disorder.

This documentary gives the lie to its own claims in that most of it simply rehashes what we already knew about Hitler. The only new thing is the claim that Hitler had Kallmann syndrome, which affects sexual development. But the physical effects of this condition vary widely and we do already have documentary evidence stating that Hitler had an undescended testicle, so, again, history is more informative than genetics.

There is also a wider issue that this documentary feeds into, the idea that Hitler was somehow uniquely evil and solely to blame for the second world war and the Holocaust. But, unfortunately, genocidal, warmongering dictators aren’t in short supply – and none could succeed without the support of many other people.

Millions voted for Hitler, other politicians backed the laws that enabled him to seize power and many officials helped implement the racist laws that led to the Holocaust. There is no need to look to genes to explain why many individuals try to become dictators – the far more pressing question is why we let them.